Behind Record U.S. Cold Snap: Canadian Air and a Jet Stream Kink

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Behind Record U.S. Cold Snap: Canadian Air and a Jet Stream Kink

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Explaining Record Cold Snap

The most intense cold snap to affect the United States in 20 years descended upon parts of the Midwest on Monday and is expected to linger through the week.

Meteorologists forecast that temperatures may dip to nearly negative 40 degrees Fahrenheit (which is also negative 40 degrees Celsius)—negative 60 degrees with wind chill—in Minnesota and as far west as Montana.

States as far south as Alabama and Georgia will also experience chillier temperatures than they've seen in years.

"The atypical part of this weather pattern is some of these really cold temperatures are going to be pressing into parts of the country that don't typically see that magnitude of cold in early winter," said Robert Oravec, a lead forecaster with the National Weather Service in College Park, Maryland.

Chilled in Canada

Experts say the unusually cold temperatures are caused by air chilled in northern Canada being blown south into the U.S.

"That air has been sitting for days in northern Canada, in almost 24-hour darkness, and over snow-covered ground that radiates heat out to space very efficiently," Masters says.

Over the weekend, the core of that cold air mass—a whirlpool of frigid air called a "polar vortex"—was shunted southward by the jet stream, a band of strong wind that blows in the upper level of the atmosphere.

"The jet stream acts as a kind of boundary between cold air in the north and warm air to the south," Masters explains.

Kink in the Jet Stream

The jet stream typically blows relatively straight west to east, but every so often a kink forms that changes its direction.

"If you get a really good kink, it allows cold air from Canada to spill southward," Masters says.

"The shape of this kink is a little bit unusual. We haven't seen something like this in about 20 years."

Oravec of the National Weather Service adds: "In this case, we're in such a weather pattern in which the polar vortex is being pushed pretty far south, almost into the Great Lakes area."

Masters, who lives in Detroit, says he plans to weather out the cold snap at home, and advised others to do the same.

The ASPCA also advises that pet owners keep their animals indoors when the mercury dips.

Dogs can lose their scent very easily in snow, and may become lost if they get off their leash. If your dog must be outdoors, ASPCA recommends owners wipe off the pooch's legs and stomach after coming back inside to prevent it from licking antifreeze, salt, or other potentially dangerous chemicals from its paws.

The good news: meteorologists predict that this cold snap will not last very long and that temperatures will return to normal by the end of the week.

"It's a very intense, but relatively short-lived, cold air outbreak," Masters says.

Allan Umscheid braves bitter wind and snow on Sunday as he blows snow off paths around his business in Lawrence, Kansas. The city got several inches of snow and has a forecast as low as minus 32 Fahrenheit (minus 36 Celsius) for Monday.

Photograph by Mike Yoder, The Journal-World/AP

Street Skiing

Ray Pass takes his cross country skis to the streets in University City, a suburb of St. Louis, Missouri, on Sunday. Pass hails originally from New York and told the media that this weekend’s snow is “nothing” compared to what he had seen before.

Photograph by J.B. Forbes, St. Louis Post-Dispatch/AP

Car Trouble

A motorist helps dig out another driver who got stuck in a snow drift on Sunday in Zionsville, Indiana. The region got several inches of snow, making roads hazardous.

Photograph by Darron Cummings, AP

Stranded

Anna Maksimkina of Yekaterinburg, Russia, rests on the floor at Kennedy International Airport in New York City on Sunday. All flights were halted after a Delta airplane from Toronto to New York skidded off the runway into a snow bank. Many travellers have experienced delays on account of the snow and unusually cold weather across much of the U.S.

Photograph by Kathy Willens, AP

Plow Time

A city snow plow works a blustery street Sunday in Springfield, Illinois. Record cold and high snowfall are making travel treacherous across much of the U.S.

Photograph by Seth Perlman, AP

Cold Walk

Tyron Smith walks against wind and snow down Bradley Avenue in Champaign, Illinois on Sunday. Weather and safety experts suggest people stay indoors during the coldest times, and to keep pets indoors as well.